Former South African President Nelson Mandela has been hospitalized, but is "responding positively" to treatment, the South African president's office said today.

Mandela was admitted to the hospital just before midnight Wednesday because of his recurring lung infection, the president's office said in a statement.

"Doctors are attending to him, ensuring that he has the best possible expert medical treatment and comfort," the government's statement said.

"The doctors advise that former President Nelson Mandela is responding positively to the treatment he is undergoing for a recurring lung infection," the presidency said in a statement. "He remains under treatment and observation in hospital."

Mandela, 94, spent 18 days in the hospital in December for a lung infection and gallstones.

"We appeal to the people of South Africa and the world to pray for our beloved Madiba and his family and to keep them in their thoughts," South African President Jacob Zuma said in the statement. "We have full confidence in the medical team and know that they will do everything possible to ensure recovery."

The anti-apartheid activist was admitted to a Pretoria hospital March 10 for routine medical tests and to "manage existing conditions in line with his age," a spokesman for the South African president's office said.

Despite rare public appearances, Mandela, who is credited with changing race relations in South Africa, remains hugely popular in the country.

Banknotes featuring Mandela's image were printed and entered into circulation in South Africa in November.

After enduring nearly three decades of prison, much of it at hard labor in a lime quarry, Mandela emerged as a gentle leader who was elected South Africa's first black president in 1994.

He was awarded the Nobel Peace Prize for his leadership in ending apartheid, and later became a global statesman who inspired millions of people around the world.

After he left office in 1999, Mandela became a global statesman, mediating conflicts in some of the world's most troubled spots.

Mandela has since retired to his childhood home in Qunu. Occasionally, the government has released photos of the former president after high-profile visitors meet with him.